1. Field of the Invention
The present invention relates to a tire air pressure detecting device. In particular, the present invention relates to a direct-type tire air pressure detecting device provided with a transmitter including a pressure sensor directly mounted on a wheel. A tire is attached to the wheel.
2. Description of the Related Art
Conventionally, a direct-type tire air pressure detecting device is known as a tire air pressure detecting device. In the direct-type tire air pressure detecting device, a transmitter including a sensor, such as a pressure sensor, is directly mounted on a wheel side of a vehicle. A tire is attached to the wheel. An antenna and a receiver are provided on the vehicle-body side. The tire air pressure detecting device operates as follows. After the transmitter transmits a detection signal from the sensor, the receiver receives the detection signal, via the antenna, and the tire air pressure detecting device performs tire air pressure detection (refer to, for example, Japanese Patent No. 3212311).
The tire air pressure detecting device adds identification (ID) information to data transmitted from the transmitter so that whether the transmitting data is that of the vehicle on which the tire air pressure detecting device is mounted (owner's vehicle) and the wheel on which the transmitter is mounted can be determined. The ID information is used to determine whether the vehicle is the owner's vehicle or another vehicle. The ID information is also used to determine the wheel on which the transmitter is mounted. The ID information is registered to the receiver in advance. When the data transmitted from the transmitter is received, the tire air pressure detecting device determines the wheel to which the data belongs using the received ID information (refer to, for example, Japanese Patent No. 3212311).
However, in a direct-type tire air pressure detecting device such as this, the transmitter mounted on the wheel is physically separated from the receiver mounted on the vehicle body. When the transmitter does not transmit data, whether this is caused by a failure in the transmitter, noise from an external source or merely as a result of the position of the transmitter is unclear. Therefore, when the transmitter does not transmit data, judgment on whether a driver is required to be notified of the data not being transmitted from the transmitter, for example, cannot be appropriately made.